[ns] multicast ttl problem?

["Joerg Walz" <jwalz@cs.umass.edu>]

Hey all,

I observed a kind of weird behavior of ns with multicast packets and TTL.
Say node A sends a MC packet to its neighboring node B with TTL of 1,
with both nodes having joined the corresponding MC group.

Now it occurs that B drops the packet at the incoming link without 
delivering the packet to its attached agents.
With a TTL of 2, B delivers the packet to the agents and forwards the packet
over its outgoing links with a TTL of 1, meaning that the next hops discard the packet.

In my understanding of the TTL field, a TTL of 1 should reach the agents of the next hop and 
then discarded there at the outgoing interface, so not to send a TTL of 0, right?
Please tell me if I am wrong.

Thanks,

Joerg 
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Joerg Walz
Student of Computer Science
University of Massachusetts, Amherst
Secure Internet and Group-Networking Lab (SIGNL)

EMail: jwalz@cs.umass.edu

"A woman's shoulders are the front lines of a mystique"
Movie - The Devil's Advocate
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